Crystal structure, theoretical studies and luminescent properties of a new borate Na3GdB8O15 with one-dimensional broad-banded anionic framework. Issue 37 (16th September 2020) - Zhao, Dan
Abstract : A new polyborate Na3 GdB8 O15 with one-dimensional chain structure was prepared, and Gd 3+ can be substituted by Ce 3+ to realize the blue light luminescence by a near-UV radiation excitation. Abstract : Inorganic borate compounds exhibit significant diversity in their structure types, which are associated with interesting optical and magnetic properties. In our work, a new rare-earth polyborate Na3 GdB8 O15 was prepared with an infinite one-dimensional (1D) broad-banded framework of [B8 O15 ]∞ running along the a -axis, in which large Gd 3+ and Na + ions reside to ensure cohesion and neutrality of the structure. The basic fundamental building block (FBB) of [B8 O15 ]∞ is B16 O32, which is composed of five BO3 and three BO4 groups and can be written as 5Δ3□: 〈2Δ□〉 − 〈Δ2□〉〈2Δ□〉. First principle studies reveal that Na3 GdB8 O15 is an indirect bandgap semiconductor and the optical absorption at 280 nm originates from the O 2− → Gd 3+ transition. Solid solutions of Na3 Gd1− x Ce x B8 O15 and Na3 Gd0.98− y Y y Ce0.02 B8 O15 were prepared and exhibited a bluish violet emissive luminescence by near-UV excitation due to the 5d 1 → 4f 1 transition of Ce 3+ . Substitution of Gd 3+ by Y 3+ enhanced the luminescence efficiency and significantly improved the thermal stability. At 423 K, the luminescence intensity of Na3 Gd0.58 Y0.4 Ce0.02 B8 O15 remained 77% of that at 298 K. We hypothesize that Na3 GdB8 O15 is a potential inorganic luminescent host matrix.